Dressing



July 18 1961 o. s. PLANTINGA ETAL 2,992,644

DRESSING Filed Jan. 2. 1959 ATTO R N EY United States Patent O FiledJan. 2, 1959, Ser. No. 784,575 '19 Claims. (Cl. 12S- 156) 'Ilhe presentinvention relates to surgical dressings and more particularly todressings wherein the surface adapted to 'face the wound is formed of aperforated smooth flexible film.

It has generally been recognized that in the natural healing of yanimalwounds, the dressing serves primarily as a protection for the woundduring the healing process. The problem with generally used dressings isthat during the healing process the eschar tends to form or grow aroundparts of the dressing, thus making i-t difficult to `later remove thedressing without tearing the eschar or scab vand thus delaying thehealing. In order to overcome this, it has heretofore been proposed touse a smooth, thin, flexible, non-water soluble film in direct contactwith the wound. The film, which may be made `of any smooth flexiblematerial, is perforated or cut to permit passage of uids through theiilm to an absorbent backing. Dressings have been proposed wherein theflexible, non-water soluble, perforated iilm is bonded to or Wrapped'around an absorbent pad. Dressings of this type are described, torexample, in the British patent to Gelinsky, 439,085, specificationacceptance date November 28, 1935 and the French patent to Weber,947,609, published July 7, 1949.

Although these hlm-faced dressings are a substantial improvement,insofar as preventing adherence of the dressing to the Wound during thehealing process, the s1ze of the holes or perforations in the film mustbe quite small in order to prevent the eschar from adhering to `theabsorbent material in the immediate vicinity of `the perforations. Also,there is a substantial tendency for the perforations to become pluggedor corked, thus decreasing the effectiveness of the absorbent backing,this p tendency being greater the smaller the perforations.

-It is an object of the present invention to prepare fhn-faced dressingsin which there is substantially less tendency for the eschar to adhereto .the absorbent backing. It is a further object of the presen-tinvention to form perforated film-faced dressings having improvedabsorbent properties. A stilfl further object 4is to form film- `faceddressings in which the per-forations can be larger while avoidingadherence to the absorbent backing, thus permitting more rapid andcomplete drainage from the wound. i

It has been discovered that the heretofore mentioned problemsencountered with perforated film-faced dressings are substantiallyovercome, and the above and other objectsl and advantages realized ifthe perforated lm is nspaced from the absorbent pad or backing used incombination with the iilm by placing a spacer or spacers, relativelynon-adherent to healing wound tissues, between the film and absorbent.Various types of spacing/elements may be used. They may take theforrn ofperforated'tissues `and nonwoven fabrics Water-repellent in nature, ofsingle threads or woven or knitted fabrics Where the threads or theyarns from which the fabrics are` prepared are formed of either a singleor a plurality of continuous synthetic filaments, or any other flexiblematerial the` absorbent backing which will not tend 'to stiffen thedressing when placedbetweenlthe absorbent andfilm and substantiallyfless adherent to healing wound tissue than i "of rra-5.

ICE

yarns formed of substantially continuous tilaments as opposed to yarnsformed of natural iibers wherein the libers are relatively short. 'Ihesesynthetic yarns, such as nylon, rayon, cellulose acetate, etc., oier asmooth continuous surface, tree of protruding ber ends. Because of theirrelatively smooth surface and yfreedom from liber ends, these syntheticyarns have substantially less tendency to become attached to the healingWound sur- `face than does a yarn formed of natural fibers. The yarn maybe a mono-filament yarn formed of a single continuous filament or amultililament yarn formed of several continuous lilaments `twistedtogether.

It is surprising that spacing elements, no thicker than a yarn having a`diameter of about 0.005 or creped lcellulose `tissue which is about0.005" Ithick, so effectively reduce any tendency Ifor the wound toadhere to the absorbent material backing the perforated iilm. Probablyone reason for this is the extreme thinness of these films. It is-generally necessary to use lms having thicknesses of less than 0.002 tohave lms of the desired flexibility. With films no thicker than this,the absorbent, back of the perforations in the film, is extremely closeto the Wound surface, and it takes very little ygrowth into theperforations or extension `of absorbent iibers through the perforationsto cause sticking at this point. However, Whatever the cause, woundrelease is substantially improved by the use of spacing elements inaccordance with the present invention.

It lis not necessary that the spacing elements, such as the threads`where individual threads of continuous monoor multi-filament syntheticyarn is used or a loose weave fabric ,formed of thesarne is employed,fall between the perforations in the iilm, but these threads can fallacross the perforations without appreciably `affecting the wound releasecharacteristics of the dressing. "The threads, however, should be ofsuch diameter as related to the size of the perforations that blockingof the perforations does not result. It is generally preferred, however,that where practical, the spacing elements -fall between `theperforations in the film.

Although it is preferred that the spacing element lie between theperforations in the film, it is extremely difiicult, particularly wherea loose weave or Aknitted fabric of continuous filament yarn is used, toaccurately `ali-gn the openings in the fabric with the openings in `theperforated lm. As a result, many of the spacing threads ings because ofthe somewhat larger perforations that can be used due to the presence ofthe spacing elements. The invention is further illustrated by thedrawings in which:

FIG. l is a perspective view of a' dressing in which `a portion of theihn is removed to show ,a woven fabric spacer; FIG. 2 is a view takenalong line 2-2 of FIG. 1; FIG. 3 is a dressing in-which individualthreads have `beenused as spacers;

FIG. 4 is an enlarged view of a section of a dressing in which awater-repellent crepe tissue is the spacing element; FIG. 5 is a bandageof the adhesive type madein'accordance with the present invention; AandFIG. `6 is a cross-sectional view taken along line'l-"V-p Referring tothe drawings, the dressing of FIG. 1 -containsan absorbent pad orbacking formed of several layers of absorbent surgical crepe tissue 1,1wrapped in a layer of carded absorbent cotton 12. The absorbent pad thusformed is enclosed in a thin lubricous` film 13 having iperforations 14,the 'film 13 being separated from the dressing by a low count wovenfabric 15 formed of a continuous filament yarn made up of a plurality ofcontinu- -ous rayon filaments. The individual threads 16 of the fabric15 serve to separate and space the carded co-tton 12 from the film 13and particularly to prevent fibers of the absorbent cotton fromextending through the perforations 14.

In assembling the dressing, the film is first preferably perforatedandthe low count continuous filament fabric then cemented to the film. Alayer of carded cotton is lthen placed on the fabric followed by a layerof absorbent lsurgical cellulose crepe tissue. The film is then folded`over `and bonded to itself, as shown at 17, either by cement or througha heat seal where the film is thermoplastic, to Vcomplete the dressing.

Although there is little chance of the spacing thread contacting thewound surface, there is always the possibility that this may occur.Continuous filament threads or yarns should therefore be used. Fabricshaving a count of 14 X l0 to 44 x 36 threads per square inch are quitesuitable. It is also generally preferred that the diameter of theindividual threads be within the range of about 0.004" to 0.00

In the modification disclosed in FIG. 3, instead of a low count fabric,individual continuous filament threads 18 are cemented to the perforatedfilm. These serve to space the film 13 from the absorbent cotton 12 inthe same manner as does the fabric 15 of FIG. l.

In FIG. 4, a section of a dressing similar to that of FIG. 1 isillustrated, the dressing differing only in the form of absorbentbacking and spacing element used. In this particular modification, theabsorbent 19 is of the conventional absorbent cotton type. The spacingelement 20 is formed of a thin sheet of water-repellent crepe tissuehaving a thickness of about 0.005. In preparing "the dressing of thisparticular embodiment, the waterrepellent crepe tissue was first bondedto the film 13 with a water-insoluble cement and the composite of filmand water-repellent crepe tissue then perforated, as by punch- `ing, toform holes Z1. The punched film and crepe tissue were then wrappedaround a pad of absorbent and the 'ends sealed to give a dressing havingthe general appear- Vthe lm 25. The adhesive-coated backing strip 22 isalso provided with'perforations 28 in the area over the absorbent pad topermit breathing of the dressing and evaporation from the absorbent 24.`In the particular embodiment illustrated, the. film facing 25 extendsbeyond the pad area and is bonded to the adhesive-coated backing at '29.The adhesive 23 ofthe backing is protected by cover strips 30, which areremoved prior to application of the bandage.

'Ihe perforations in the lubricous film should be present in sufficientnumber to permit ready passage of excretions from the wound surface intothe absorbent backing. Itis 'generally preferred that these perforationshavean open areaeqnivalent to a circle having a diameter of 0.01 to0.2"and be present in sufficient number and so dispersed -a,toprovide,foreach square-inch of film surface, an open area of'at least 0.0075 sq.in., the open area generally varying within the range of 0.1 to 0.4square inch per square inch of film.

In the preferred practice of the present invention, polyethyleneterephthalate films, 1such as sold under the trademark Mylarj are usedbecause of their flexibility, resistance to high temperatures, such asused in steam sterilization, their strength, and somewhat lower cost ascompared to other suitable film materials. However, any film may be usedas Vlong as it is sufficiently exible, insoluble in water, substantiallyinert to the wound excretions, and sufficiently thin to readily adaptitself to the surface conformity cf a wound. Other film materials thathave been successfully used are films made of high pressurepolyethylene, low pressure polyethylene, irradiated polyethylene,polyvinyl chloride, plain parchment paper,

cellulose acetate, polyvinylidene chloride and nylon.

The film should be quite thin, film thicknesses of less than 0.001generally being preferred. 'Ihere is no limit to film thinness exceptstrength.

Where the perforated lm is bonded to the spacer by an adhesive, theadhesive used should preferably be nonwater soluble and one that doesnot interfere with the healing process or tend to stifen the filmfacing. It should also maintain its bond after sterilization. 'Illebonding may be done either by a suitable cement or by heat sealing ifthe film is of a thermoplastic nature.

Although various modifications of the invention have been described inorder to illustrate the same, the invenytion is not limited to thesespecific modifications which are given for the purpose of illustrationonly. The inven- Ition is to be limited only in accordance with theappended claims.

Having thus described our invention, we claim:

1. A dressing comprising a pad formed of Vabsorbent material having anouter facing on at least one side formed of a perforated, flexible,water insoluble, lubricous film and flexible lrelatively non-woundadherent spacing elements between said fllm and said labsorbent pad.

2. A dressing of claim l wherein the spacing element is threads ofcontinuous filament yarn.

3. A dressing of claim 2 wherein the spacing threads yare woven into alow count fabric. Y

4. A dressing of cl-aim 3 wherein the fabric has a thread count 0f about14 x l0 to 44 X 36 per square inch.

5. A dressing of clainr 2 wherein the threads are formed of amonofilament yarn.

6. A dressing of claim 2 wherein the substantially con- 'tinuousfilament yarn is knitted into a loose knit non-absorbent fabric, whichacts as the spacer.

7. A dressing of claim l wherein the spacing element is a thin,perforated sheet of water-repellent crepe tissue. 8. A dressingcomprising a perforated, flexible, water insoluble, lubricous filmhaving bonded thereto a thin sheet of water-repellent crepe tissuepaper, the perfora- .tions in said film passing through said paper andan absorbent pad in contact with said crepe tissue.

9. A dressing comprising an absorbent pad, a flexible non-absorbentperforated film on both sides of said pad, the flhn on at least one sidebeing formed of a flexible, water insoluble, lubricous materialrelatively non-adhering to healing tissue, a relatively non-woundadherent spacing element being positioned between said absorbent pad andsaid lubricous film.

10. A dressing of claim 9 in which said spacing element consists of aplurality of substantially continuous filament threads extending acrossthe face of said absorbent pad.

11. A dressing of claim 10 in which said threads are woven into a fabrichaving a count of 14 X 10 to 44 X 36 threads per square inch.

l2. A dressing of claim 10 wherein the substantially continuous filamentthreads are knitted into a loose knit fabric which acts `as the spacer.Y

13. A dressing of claim 9 in which the spacingelement is a thin,perforated sheet of water-repellent tissue paper, the perforations insaid sheet being in alignment with the perforations in said lubrioous lmfacing.

14. A dressing comprising a-n outer Wrapping of a perforated lubricousfilm, a -low count fabric woven of a continuous filament yarn in contactwith said lm, an absorbent cotton layer in contact with said low countfabric and an absorbent crepe tissue paper in contact with saidabsorbent cotton.

15. An adhesive dressing comprising .an adhesive-coated base of exiblematerial, an absorbent pad smaller than said base supported on theadhesive-coated side thereof, a perforated, exible non-water soluble lmcov ering said pad and a relatively non-wound adherent spacing elementbetween said lm and said pad.

16. A dressing of claim 15 wherein said spacing ele ments aresubstantially continuous filament threads.

17. A dressing of claim 16 wherein the spacing threads are Woven into alow count fabric.

18. A dressing of claim 16 wherein the substantially continuous lamentthreads are knitted into a loose knit fabric which :acts as the spacer.

19. A dressing of claim 15 wherein the spacing element is a thi-n,perforated sheet of water-repellent crepe tissue, the perforations insaid sheet being in valignment with the perforations in the lm facing.

References Cited in the file of this patent UNITED STATES PATENTS2,923,298 Dockstader Feb. 2, 1960 FOREIGN PATENTS 22,327 Great Britain1910 776.408 Great Britain June S, 1947 661,113 France Feb. 26, 1929

